Providing compound image of doppler spectrum images in ultrasound system

ABSTRACT

There are provided embodiments for providing a compound image of Doppler spectrum images corresponding to at least two sample volumes. In one embodiment, by way of non-limiting example, an ultrasound system comprises: a processing unit configured to form at least two Doppler spectrum images corresponding to at least two sample volumes based on ultrasound data corresponding to the at least two sample volume, the processing unit being further configured to perform an image process for forming a compound image upon the at least two Doppler spectrum images to form the compound image.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from Korean Patent ApplicationNo. 10-2011-0144445 filed on Dec. 28, 2011, the entire subject matter ofwhich is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure generally relates to ultrasound systems, and moreparticularly to providing a compound image of Doppler spectrum images inan ultrasound system.

BACKGROUND

An ultrasound system has become an important and popular diagnostic toolsince it has a wide range of applications. Specifically, due to itsnon-invasive and non-destructive nature, the ultrasound system has beenextensively used in the medical profession. Modern high-performanceultrasound systems and techniques are commonly used to producetwo-dimensional or three-dimensional ultrasound images of internalfeatures of target objects (e.g., human organs).

The ultrasound system may provide ultrasound images of various modesincluding a brightness mode image representing reflection coefficientsof ultrasound signals (i.e., ultrasound echo signals) reflected from atarget object of a living body with a two-dimensional image, a Dopplermode image representing velocity of a moving target object with spectralDoppler by using a Doppler effect, a color Doppler mode imagerepresenting velocity of the moving target object with colors by usingthe Doppler effect, an elastic image representing mechanicalcharacteristics of tissues before and after applying compressionthereto, and the like.

The ultrasound system may transmit the ultrasound signals to the livingbody and receive the ultrasound echo signals from the living body toform Doppler signals corresponding to a region of interest, which is seton the brightness mode image. The ultrasound system may further form thecolor Doppler mode image representing the velocity of the moving targetobject with colors based on the Doppler signals. In particular, thecolor Doppler image may represent the motion of the target object (e.g.,blood flow) with the colors. The color Doppler image may be used todiagnose disease of a blood vessel, a heart and the like. However, it isdifficult to represent an accurate motion of the target object (e.g.,blood flow) since the respective colors indicated by a motion value is afunction of the velocity of the target object, which moves forward in atransmission direction of the ultrasound signals and moves backward inthe transmission direction of the ultrasound signals.

Particularly, the ultrasound system may set a sample volume on thebrightness mode image, transmit ultrasound signals to the living bodybased on an ensemble number, and receive ultrasound echo signals fromthe living to form a Doppler spectrum image corresponding to the samplevolume.

SUMMARY

There are provided embodiments for forming Doppler spectrum imagescorresponding to at least two sample volumes and compounding the Dopplerspectrum images to provide a compound image.

In one embodiment, by way of non-limiting example, an ultrasound systemcomprises: a processing unit configured to form at least two Dopplerspectrum images corresponding to at least two sample volumes based onultrasound data corresponding to the at least two sample volume, theprocessing unit being further configured to perform an image process forforming a compound image upon the at least two Doppler spectrum imagesto form the compound image.

In another embodiment, there is provided a method of providing acompound image, comprising: a) forming at least two Doppler spectrumimages corresponding to at least two sample volumes based on ultrasounddata corresponding to the at least two sample volume; and b) performingan image process for forming a compound image upon the at least twoDoppler spectrum images to form the compound image.

The Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key or essentialfeatures of the claimed subject matter, nor is it intended to be used indetermining the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an illustrative embodiment of anultrasound system.

FIG. 2 is a schematic diagram showing an example of a brightness modeimage and sample volumes.

FIG. 3 is a block diagram showing an illustrative embodiment of anultrasound data acquiring unit.

FIG. 4 is a schematic diagram showing an example of sampling data andpixels of an ultrasound image.

FIGS. 5 to 8 are schematic diagrams showing examples of performing areception beam-forming.

FIG. 9 is a schematic diagram showing an example of setting weights.

FIG. 10 is a schematic diagram showing an example of setting a samplingdata set.

FIG. 11 is a flow chart showing a process of forming a compound image ofDoppler spectrum images.

FIG. 12 is a schematic diagram showing an example of the sample volumesand the Doppler spectrum images.

FIGS. 13 to 15 are schematic diagrams showing examples of the compoundimages.

DETAILED DESCRIPTION

A detailed description may be provided with reference to theaccompanying drawings. One of ordinary skill in the art may realize thatthe following description is illustrative only and is not in any waylimiting. Other embodiments of the present invention may readily suggestthemselves to such skilled persons having the benefit of thisdisclosure.

Referring to FIG. 1, an ultrasound system 100 in accordance with anillustrative embodiment is shown. As depicted therein, the ultrasoundsystem 100 may include a user input unit 110.

The user input unit 110 may be configured to receive input informationfrom a user. In one embodiment, the input information may includeinformation for setting at least two sample volumes (e.g., SV₁, SV₂,SV₃) on a brightness mode image BI, as shown in FIG. 2. That is, theinput information may include the number, position and size of thesample volumes. However, it should be noted herein that the inputinformation may not be limited thereto. In FIG. 2, the reference numeralBV represents a blood vessel. The user input unit 110 may include acontrol panel, a track ball, a touch screen, a mouse, a keyboard and thelike.

The ultrasound system 100 may further include an ultrasound dataacquiring unit 120. The ultrasound data acquiring unit 120 may beconfigured to transmit ultrasound signals to a living body. The livingbody may include target objects (e.g., blood vessel, heart, blood flow,etc). The ultrasound data acquiring unit 120 may be further configuredto receive ultrasound signals (i.e., ultrasound echo signals) from theliving body to acquire ultrasound data corresponding to an ultrasoundimage.

FIG. 3 is a block diagram showing an illustrative embodiment of theultrasound data acquiring unit. Referring to FIG. 3, the ultrasound dataacquiring unit 120 may include an ultrasound probe 310.

The ultrasound probe 310 may include a plurality of elements (not shown)for reciprocally converting between ultrasound signals and electricalsignals. The ultrasound probe 310 may be configured to transmit theultrasound signals to the living body. The ultrasound probe 310 may befurther configured to receive the ultrasound echo signals from theliving body to output electrical signals (hereinafter referred to as“reception signals”). The reception signals may be analog signals. Theultrasound probe 310 may include a convex probe, a linear probe and thelike.

The ultrasound data acquiring unit 120 may further include atransmitting section 320. The transmitting section 320 may be configuredto control the transmission of the ultrasound signals. The transmittingsection 320 may be further configured to generate electrical signals(hereinafter referred to as “transmission signals”) in consideration ofthe elements.

In one embodiment, the transmitting section 320 may be configured togenerate transmission signals (hereinafter referred to as “brightnessmode transmission signals”) for obtaining the brightness mode image BIin consideration of the elements. Thus, the ultrasound probe 310 may beconfigured to convert the brightness mode transmission signals providedfrom the transmitting section 320 into the ultrasound signals, transmitthe ultrasound signals to the living body, and receive the ultrasoundecho signals from the living body to output reception signals(hereinafter referred to as “brightness mode reception signals”).

The transmitting section 320 may be further configured to generatetransmission signals (hereinafter referred to as “Doppler modetransmission signals”) for obtaining Doppler spectrum imagescorresponding to the at least two sample volumes based on an ensemblenumber. The ensemble number may represent the number of transmitting andreceiving the ultrasound signals. Thus, the ultrasound probe 310 may beconfigured to convert the Doppler mode transmission signals providedfrom the transmitting section 320 into the ultrasound signals andtransmit the ultrasound signals to the living body. The ultrasoundsignals transmitted from the ultrasound probe 310 may be the plane wavesignals. The ultrasound probe 310 may be further configured to receivethe ultrasound echo signals from the living body in at least onereception direction to output reception signals (hereinafter referred toas “Doppler mode reception signals”).

The ultrasound data acquiring unit 120 may further include a receivingsection 330. The receiving section 330 may be configured to perform ananalog-digital conversion upon the reception signals provided from theultrasound probe 310 to form sampling data. The receiving section 330may be also configured to perform a reception beam-forming upon thesampling data in consideration of the elements to form reception-focuseddata. The reception beam-forming will be described below in detail.

In one embodiment, the receiving section 330 may be configured toperform the analog-digital conversion upon the brightness mode receptionsignals provided from the ultrasound probe 310 to form sampling data(hereinafter referred to as “brightness mode sampling data”). Thereceiving section 330 may be further configured to perform the receptionbeam-forming upon the brightness mode sampling data to formreception-focused data (hereinafter referred to as “brightness modereception-focused data”).

The receiving section 330 may be further configured to perform theanalog-digital conversion upon the Doppler mode reception signalsprovided from the ultrasound probe 310 to form sampling data(hereinafter referred to as “Doppler mode sampling data”). The receivingsection 330 may be also configured to perform the reception beam-formingupon the Doppler mode sampling data to form reception-focused data(hereinafter referred to as “Doppler mode reception-focused data”)corresponding to the at least two sample volumes.

For example, the receiving section 330 may perform the receptionbeam-forming upon the Doppler mode sampling data to form first Dopplermode reception-focused data corresponding to the sample volume SV₁. Thereceiving section 330 may further perform the reception beam-formingupon the Doppler mode sampling data to form second Doppler modereception-focused data corresponding to the sample volume SV₂. Thereceiving section 330 may also perform the reception beam-forming uponthe Doppler mode sampling data to form third Doppler modereception-focused data corresponding to the sample volume SV₃.

The reception beam-forming may be described with reference to theaccompanying drawings.

In one embodiment, the receiving section 330 may be configured toperform the analog-digital conversion upon the reception signalsprovided through a plurality of channels CH_(k), wherein 1≦k≦N, from theultrasound probe 310 to form sampling data S_(i,j), wherein the i and jare a positive integer, as shown in FIG. 4. The sampling data S_(i,j)may be stored in a storage unit 140. The receiving section 330 may befurther configured to detect pixels corresponding to the sampling databased on positions of the elements and positions (orientation) of pixelsof the ultrasound image UI with respect to the elements. That is, thereceiving section 330 may select the pixels, which the respectivesampling data are used as pixel data thereof, during the receptionbeam-forming based on the positions of the elements and the orientationof the respective pixels of the ultrasound image UI with respect to theelements. The receiving section 330 may be configured to cumulativelyassign the sampling data corresponding to the selected pixels as thepixel data.

For example, the receiving section 330 may be configured to set a curve(hereinafter referred to as “reception beam-forming curve”) CV_(6,3) forselecting pixels, which the sampling data S_(6,3) are used as the pixeldata thereof, during the reception beam-forming based on the positionsof the elements and the orientation of the respective pixels of theultrasound image UI with respect to the elements, as shown in FIG. 5.The receiving section 330 may be further configured to detect the pixelsP_(3,1), P_(3,2), P_(4,2), P_(4,3), P_(4,4), P_(4,5), P_(4,6), P_(4,7),P_(4,8), P_(4,9), . . . P_(3,N) corresponding to the receptionbeam-forming curve CV_(6,3) from the pixels P_(a,b) of the ultrasoundimage UI, wherein 1≦b≦N. That is, the receiving section 330 may selectthe pixels P_(3,1), P_(3,2), P_(4,2), P_(4,3), P_(4,4), P_(4,5),P_(4,6), P_(4,7), P_(4,8), P_(4,9), . . . P_(3,N) on which the receptionbeam-forming curve CV_(6,3) passes among the pixels P_(a,b) of theultrasound image UI. The receiving section 330 may be also configured toassign the sampling data S_(6,3) to the selected pixels P_(3,1),P_(3,2), P_(4,2), P_(4,3), P_(4,4), P_(4,5), P_(4,6), P_(4,7), P_(4,8),P_(4,9), . . . P_(3,N), as shown in FIG. 6.

Thereafter, the receiving section 330 may be configured to set areception beam-forming curve CV_(6,4) for selecting pixels, which thesampling data S_(6,4) are used as the pixel data thereof, during thereception beam-forming based on the positions of the elements and theorientation of the respective pixels of the ultrasound image UI withrespect to the elements, as shown in FIG. 7. The receiving section 330may be further configured to detect the pixels P_(2,1), P_(3,1),P_(3,2), P_(4,2), P_(4,3), P_(4,4), P_(5,4), P_(5,5), P_(5,6), P_(5,7),P_(5,8), P_(4,9), P_(5,9), . . . P_(4,N), P_(3,N) corresponding to thereception beam-forming curve CV_(6,4) from the pixels P_(a,b) of theultrasound image UI. That is, the receiving section 330 may select thepixels P_(2,1), P_(3,1), P_(3,2), P_(4,2), P_(4,3), P_(4,4), P_(5,4),P_(5,5), P_(5,6), P_(5,7), P_(5,8), P_(4,9), P_(5,9), . . . P_(4,N),P_(3,N) on which the reception beam-forming curve CV_(6,4) passes amongthe pixels P_(a,b) of the ultrasound image UI. The receiving section 330may be further configured to assign the sampling data S_(6,4) to theselected pixels P_(2,1), P_(3,1), P_(3,2), P_(4,2), P_(4,3), P_(4,4),P_(5,4), P_(5,5), P_(5,6), P_(5,7), P_(5,8), P_(5,9), . . . P_(4,N),P_(3,N), as shown in FIG. 8. In this way, the respective sampling data,which are used as the pixel data, may be cumulatively assigned to thepixels as the pixel data.

The receiving section 330 may be configured to perform the receptionbeam-forming (i.e., summing) upon the sampling data, which arecumulatively assigned to the respective pixels P_(a,b) of the ultrasoundimage UI to form the reception-focused data.

In another embodiment, the receiving section 330 may be configured toperform the analog-digital conversion upon the reception signalsprovided through the plurality of channels CH_(k) from the ultrasoundprobe 310 to form the sampling data S_(i,j), as shown in FIG. 4. Thesampling data S_(i,j) may be stored in the storage unit 140. Thereceiving section 330 may be further configured to detect pixelscorresponding to the sampling data based on the positions of theelements and the position (orientation) of the pixels of the ultrasoundimage UI with respect to the elements. That is, the receiving section330 may select the pixels, which the respective sampling data are usedas the pixel data thereof, during the reception beam-forming based onthe positions of the elements and the orientation of the respectivepixels of the ultrasound image UI with respect to the elements. Thereceiving section 330 may be configured to cumulatively assign thesampling data corresponding to the selected pixels as the pixel data.The receiving section 330 may be further configured to determine pixelsexisting in the same column among the selected pixels. The receivingsection 330 may be also configured to set weights corresponding to therespective determined pixels. The receiving section 330 may beadditionally configured to apply the weights to the sampling data of therespective pixels.

For example, the receiving section 330 may be configured to set thereception beam-forming curve CV_(6,3) for selecting pixels, which thesampling data S_(6,3) are used as the pixel data thereof, during thereception beam-forming based on the positions of the elements and theorientation of the respective pixels of the ultrasound image UI withrespect to the elements, as shown in FIG. 5. The receiving section 330may be further configured to detect the pixels P_(3,1), P_(3,2),P_(4,2), P_(4,3), P_(4,4), P_(4,5), P_(4,6), P_(4,7), P_(4,8), P_(4,9),. . . P_(3,N) corresponding to the reception beam-forming curve CV_(6,3)from the pixels P_(a,b) of the ultrasound image UI, wherein 1≦a≦M,1≦b≦N. That is, the receiving section 330 may select the pixels P_(3,1),P_(3,2), P_(4,2), P_(4,3), P_(4,4), P_(4,5), P_(4,6), P_(4,7), P_(4,8),P_(4,9), . . . P_(IN) on which the reception beam-forming curve CV_(6,3)passes among the pixels P_(a,b) of the ultrasound image UI. Thereceiving section 330 may be also configured to assign the sampling dataS_(6,3) to the selected pixels P_(3,1), P_(3,2), P_(4,2), P_(4,3),P_(4,4), P_(4,5), P_(4,6), P_(4,7), P_(4,8), P_(4,9), . . . P_(3,N), asshown in FIG. 6. The receiving section 330 may be further configured todetermine pixels P_(3,2) and P_(4,2), which exist in the same columnamong the selected pixels P_(3,1), P_(3,2), P_(4,2), P_(4,3), P_(4,4),P_(4,5), P_(4,6), P_(4,7), P_(4,8), P_(4,9), . . . P_(3,N). Thereceiving section 330 may be further configured to calculate a distanceW₁ from a center of the determined pixel P_(3,2) to the receptionbeam-forming curve CV_(6,3) and a distance W₂ from a center of thedetermined pixel P_(4,2) to the reception beam-forming curve CV_(6,3),as shown in FIG. 9. The receiving section 330 may be additionallyconfigured to set a first weight α₁ corresponding to the pixel P_(3,2)based on the distance W₁ and a second weight α₂ corresponding to thepixel P_(4,2) based on the distance W₂. The first weight α₁ and thesecond weight α₂ may be set to be in proportional to or in inverseproportional to the calculated distances. The receiving section 330 maybe further configured to apply the first weight α₁ to the sampling dataS_(6,3) assigned to the pixel P_(3,2) and to apply the second weight α₂to the sampling data S_(6,3) assigned to the pixel P_(4,2). Thereceiving section 330 may be configured to perform the above processupon the remaining sampling data.

The receiving section 330 may be configured to perform the receptionbeam-forming upon the sampling data, which are cumulatively assigned tothe respective pixels P_(a,b) of the ultrasound image UI to form thereception-focused data.

In yet another embodiment, the receiving section 330 may be configuredto perform the analog-digital conversion upon the reception signalsprovided through the plurality of channels CH_(k) from the ultrasoundprobe 310 to form the sampling data S_(i,j), as shown in FIG. 4. Thesampling data S_(i,j) may be stored in the storage unit 140. Thereceiving section 330 may be further configured to set a sampling dataset based on the sampling data S_(i,j). That is, The receiving section330 may set the sampling data set for selecting pixels, which thesampling data S_(i,j) are used as the pixel data thereof, during thereception beam-forming.

For example, the receiving section 330 may be configured to set thesampling data S_(1,1), S_(1,4), S_(1,t), S_(2,1), S_(2,4), . . .S_(2,t), S_(p,t) as the sampling data set (denoted by a box) forselecting the pixels, which the sampling data S are used as the pixeldata thereof, during the reception beam-forming, as shown in FIG. 10.

The receiving section 330 may be further configured to detect the pixelscorresponding to the respective sampling data of the sampling data setbased on the positions of the elements and the positions (orientation)of the respective pixels of the ultrasound image UI with respect to theelements. That is, the receiving section 330 may select the pixels,which the respective sampling data of the sampling data set are used asthe pixel data thereof, during the reception beam-forming based on thepositions of the elements and the orientation of the respective pixelsof the ultrasound image UI with respect to the elements. The receivingsection 330 may be further configured to cumulatively assign thesampling data to the selected pixels in the same manner with the aboveembodiments. The receiving section 330 may be also configured to performthe reception beam-forming upon the sampling data, which arecumulatively assigned to the respective pixels of the ultrasound imageUI to form the reception-focused data.

In yet another embodiment, the receiving section 330 may be configuredto perform a down-sampling upon the reception signals provided throughthe plurality of channels CH_(k) from the ultrasound probe 310 to formdown-sampling data. As described above, the receiving section 330 may befurther configured to detect the pixels corresponding to the respectivesampling data, based on the positions of the elements and the positions(orientation) of the respective pixels of the ultrasound image UI withrespect to the elements. That is, the receiving section 330 may selectthe pixels, which the respective sampling data are used as the pixeldata thereof, during the reception beam-forming based on the positionsof the elements and the orientation of the pixels of the ultrasoundimage UI with respect to the elements. The receiving section 330 may befurther configured to cumulatively assign the respective sampling datato the selected pixels in the same manner of the above embodiments. Thereceiving section 330 may be further configured to perform the receptionbeam-forming upon the sampling data, which are cumulatively assigned tothe respective pixels of the ultrasound image UI to form thereception-focused data.

However, it should be noted herein that the reception beam-forming maynot be limited thereto.

Referring back to FIG. 3, the ultrasound data acquiring unit 120 mayfurther include an ultrasound data forming section 340. The ultrasounddata forming section 340 may be configured to form the ultrasound datacorresponding to the ultrasound image based on the reception-focuseddata provided from the receiving section 330. The ultrasound dataforming section 340 may be further configured to perform a signalprocess (e.g., gain control, etc) upon the reception-focused data.

In one embodiment, the ultrasound data forming section 340 may beconfigured to form ultrasound data (hereinafter referred to as“brightness mode ultrasound data”) corresponding to the brightness modeimage BI based on the brightness mode reception-focused data providedfrom the receiving section 330. The brightness mode ultrasound data mayinclude radio frequency data. However, it should be noted herein thatthe brightness mode ultrasound data may not be limited thereto.

The ultrasound data forming section 340 may be further configured toform ultrasound data (hereinafter referred to as “Doppler modeultrasound data”) corresponding to the at least two sample volumes basedon the Doppler mode reception-focused data provided from the receivingsection 330. The Doppler mode ultrasound data may includein-phase/quadrature data. However, it should be noted herein that theDoppler mode ultrasound data may not be limited thereto.

For example, the ultrasound data forming section 340 may form firstDoppler mode ultrasound data corresponding to the sample volume SV₁based on the first Doppler mode reception-focused data provided from thereceiving section 330. The ultrasound data forming section 340 mayfurther form second Doppler mode ultrasound data corresponding to thesample volume SV₂ based on the second Doppler mode reception-focuseddata provided from the receiving section 330. The ultrasound dataforming section 340 may further form third Doppler mode ultrasound datacorresponding to the sample volume SV₃ based on the third Doppler modereception-focused data provided from the receiving section 330.

Referring back to FIG. 1, the ultrasound system 100 may further includea processing unit 130 in communication with the user input unit 110 andthe ultrasound data acquiring unit 120. The processing unit 130 mayinclude a central processing unit, a microprocessor, a graphicprocessing unit and the like.

FIG. 11 is a flow chart showing a process of forming a compound image ofthe Doppler spectrum images. The processing unit 130 may be configuredto form the brightness mode image BI based on the brightness modeultrasound data provided from the ultrasound data acquiring unit 120, atstep S 1102 in FIG. 11. The brightness mode image BI may be displayed ona display unit 150.

The processing unit 130 may be configured to set the at least two samplevolumes on the brightness mode image BI based on the input informationprovided from the user input unit 110, at step S1104 in FIG. 11. Thus,the ultrasound data acquiring unit 120 may be configured to transmit theultrasound signals to the living body and receive the ultrasound echosignals from the living body to acquire the Doppler mode ultrasound datacorresponding to the at least two sample volumes.

The processing unit 130 may be configured to form Doppler signalscorresponding to each of the at least two sample volumes based on theDoppler mode ultrasound data provided from the ultrasound data acquiringunit 120, at step S1106 in FIG. 11. The methods of forming the Dopplersignals are well known in the art. Thus, they have not been described indetail so as not to unnecessarily obscure the present disclosure.

For example, the processing unit 130 may form first Doppler signalscorresponding to the sample volume SV₁ based on the first Doppler modeultrasound data provided from the ultrasound data acquiring unit 120.The processing unit 130 may further form second Doppler signalscorresponding to the sample volume SV₂ based on the second Doppler modeultrasound data provided from the ultrasound data acquiring unit 120.The processing unit 130 may further form third Doppler signalscorresponding to the sample volume SV₃ based on the third Doppler modeultrasound data provided from the ultrasound data acquiring unit 120.

The processing unit 130 may be configured to form the at least twoDoppler spectrum images corresponding to the at least two sample volumesbased on the Doppler signals corresponding to the at least two samplevolumes, at step S 1108 in FIG. 11. The methods of forming the Dopplerspectrum image are well known in the art. Thus, they have not beendescribed in detail so as not to unnecessarily obscure the presentdisclosure.

For example, the processing unit 130 may form a first Doppler spectrumimage corresponding to the sample volume SV₁ based on the first Dopplersignals corresponding to the sample volume SV₁. The processing unit 130may further form a second Doppler spectrum image corresponding to thesample volume SV₂ based on the second Doppler signals corresponding tothe sample volume SV₂. The processing unit 130 may further form a thirdDoppler spectrum image corresponding to the sample volume SV₃ based onthe third Doppler signals corresponding to the sample volume SV₃.

The processing unit 130 may be configured to perform an image processfor forming a compound image of the at least two Doppler spectrum imagesupon the at least two Doppler spectrum images to form the compoundimage, at step S1110 in FIG. 11. In one embodiment, the image processmay include an image process for adding pixel values (i.e., brightnessvalues) corresponding to pixels of same positions on the at least twoDoppler spectrum images, an image process for subtracting the pixelvalues (i.e., brightness values) corresponding to the pixels of the samepositions on the at least two Doppler spectrum images, an image processfor multiplying the pixel values (i.e., brightness values) correspondingto the pixels of the same positions on the at least two Doppler spectrumimages, an image process for performing various blending processes amongthe at least two Doppler spectrum images and the like.

As one example, the processing unit 130 may detect the pixels of thesame positions on the first Doppler spectrum image to the third Dopplerspectrum image, based on positions (orientation) of pixels correspondingto each of the first Doppler spectrum image to the third Dopplerspectrum image. The processing unit 130 may further perform the imageprocess for adding the pixel values corresponding to the detected pixelsto form the compound image CI₁ as shown in FIG. 13.

As another example, the processing unit 130 may detect the pixels of thesame positions on the first Doppler spectrum image to the third Dopplerspectrum image, based on the positions (orientation) of the pixelscorresponding to each of the first Doppler spectrum image to the thirdDoppler spectrum image. The processing unit 130 may further perform theimage process for subtracting the pixel values corresponding to thedetected pixels to form the compound image CI₂ as shown in FIG. 14.

As yet another example, the processing unit 130 may detect the pixels ofthe same positions on the first Doppler spectrum image to the thirdDoppler spectrum image, based on the positions (orientation) of thepixels corresponding to each of the first Doppler spectrum image to thethird Doppler spectrum image. The processing unit 130 may furtherperform the image process for multiplying the pixel values correspondingto the detected pixels to form the compound image CI₃ as shown in FIG.15.

Optionally, the processing unit 130 may be configured to perform a mentrace upon the compound image.

Referring back to FIG. 1, the ultrasound system 100 may further includethe storage unit 140. The storage unit 140 may store the ultrasound data(i.e., brightness mode ultrasound data and Doppler mode ultrasound data)acquired by the ultrasound data acquiring unit 120. The storage unit 140may further store the Doppler signals formed by the processing unit 130.The storage unit 140 may further store the input information received bythe user input unit 110. The storage unit 140 may further store thebrightness mode image, the Doppler spectrum images, and the compoundimage.

The ultrasound system 100 may further include the display unit 150. Thedisplay unit 150 may be configured to display the brightness mode imageformed by the processing unit 130. The display unit 150 may be furtherconfigured to display the Doppler spectrum images formed by theprocessing unit 130. The display unit 150 may be further configured todisplay the compound image formed by the processing unit 130.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, numerous variations andmodifications are possible in the component parts and/or arrangements ofthe subject combination arrangement within the scope of the disclosure,the drawings and the appended claims. In addition to variations andmodifications in the component parts and/or arrangements, alternativeuses will also be apparent to those skilled in the art.

What is claimed is:
 1. An ultrasound system, comprising: a processingunit configured to form at least two Doppler spectrum imagescorresponding to at least two sample volumes based on ultrasound datacorresponding to the at least two sample volume, the processing unitbeing further configured to perform an image process for forming acompound image upon the at least two Doppler spectrum images to form thecompound image.
 2. The ultrasound system of claim 1, wherein the imageprocess includes at least one of a first image process for adding pixelvalues corresponding to pixels of same positions on the at least twoDoppler spectrum images, a second image process for subtracting thepixel values corresponding to the pixels of the same positions on the atleast two Doppler spectrum images, a third image process for multiplyingthe pixel values corresponding to the pixels of the same positions onthe at least two Doppler images, and a fourth image process forperforming a blending process among the at least two Doppler spectrumimages.
 3. The ultrasound system of claim 1, further comprising: anultrasound data acquiring unit configured to transmit ultrasound signalsto a living body in at least one transmission direction and receiveultrasound echo signals from the living body in at least one receptiondirection to acquire the ultrasound data corresponding to the at leasttwo sample volumes.
 4. The ultrasound system of claim 3, wherein theultrasound signals include unfocused signals or focused signals.
 5. Theultrasound system of claim 3, wherein the ultrasound data acquiring unitis configured to: form reception signals based on the ultrasound echosignals; perform an analog-digital conversion upon the reception signalsto form a plurality of sampling data; detect pixels corresponding toeach of the sampling data from the pixels of the Doppler spectrum imagesto cumulatively assign the sampling data to the detected pixels; performreception beam-forming upon the sampling data assigned to the detectedpixels to form reception-focused data corresponding to the at least twosample volumes; and form the ultrasound data corresponding to the atleast two sample volume based on the reception-focused data.
 6. Theultrasound system of claim 5, wherein the ultrasound data acquiring unitis configured to: set a beam-forming curve for selecting pixels whichthe respective sampling data are used as pixel data thereof; and selectthe pixels corresponding to the beam-forming curve.
 7. The ultrasoundsystem of claim 5, wherein the ultrasound data acquiring unit is furtherconfigured to: determine pixels existing in the same column of theDoppler spectrum images among the selected pixels; set weightscorresponding to the respective determined pixels; and apply the weightsto the sampling data of the respective determined pixels.
 8. Theultrasound system of claim 7, wherein the ultrasound data acquiring unitis further configured to: calculate distances from a center of therespective determined pixels to the beam-forming curve; and set theweights based on the calculated distances.
 9. The ultrasound system ofclaim 8, wherein the weights are set to be in proportional to or inverseproportional to the calculated distances.
 10. The ultrasound system ofclaim 5, wherein the ultrasound data acquiring unit is furtherconfigured to: set a sampling data set for selecting pixels which therespective sampling data are used as pixels data thereof among thesampling data; and select pixels corresponding to respective samplingdata of the sampling data set.
 11. The ultrasound system of claim 5,wherein the ultrasound data acquiring unit is further configured to:perform a down-sampling process upon the reception signals to formdown-sampled data.
 12. A method of providing a compound image,comprising: a) forming at least two Doppler spectrum imagescorresponding to at least two sample volumes based on ultrasound datacorresponding to the at least two sample volume; and b) performing animage process for forming a compound image upon the at least two Dopplerspectrum images to form the compound image.
 13. The method of claim 12,wherein the image process includes at least one of a first image processfor adding pixel values corresponding to pixels of same positions on theat least two Doppler spectrum images, a second image process forsubtracting the pixel values corresponding to the pixels of the samepositions on the at least two Doppler spectrum images, a third imageprocess for multiplying the pixel values corresponding to the pixels ofthe same positions on the at least two Doppler images, and a fourthimage process for performing a blending process among the at least twoDoppler spectrum images.
 14. The method of claim 12, further comprising:transmitting ultrasound signals to a living body including the targetobject in at least one transmission direction and receiving ultrasoundecho signals from the living body in at least one reception direction toacquire the ultrasound data corresponding to the at least two samplevolumes, prior to performing the step a).
 15. The method of claim 14,wherein the ultrasound signals include unfocused signals or focusedsignals.
 16. The method of claim 14, wherein the step of acquiring theultrasound data, further comprises: forming reception signals based onthe ultrasound echo signals; performing an analog-digital conversionupon the reception signals to form a plurality of sampling data;detecting pixels corresponding to each of the sampling data from thepixels of the Doppler spectrum images to cumulatively assign thesampling data to detected pixels; performing reception beam-forming uponthe sampling data assigned to the detected pixels to formreception-focused data corresponding to the at least two sample volumes;and forming the ultrasound data corresponding to each of the at leasttwo sample volumes based on the reception-focused data.
 17. The methodof claim 16, wherein the step of detecting the pixels corresponding toeach of the sampling data, comprises: setting a beam-forming curve forselecting pixels which the respective sampling data are used as pixeldata thereof; and selecting the pixels corresponding to the beam-formingcurve.
 18. The method of claim 17, wherein the step of acquiring theultrasound data, further comprises: determining pixels existing in thesame column of the Doppler spectrum images among the selected pixels;setting weights corresponding to the respective determined pixels; andapplying the weights to the sampling data of the respective determinedpixels.
 19. The method of claim 18, wherein the step of setting theweights, comprises: calculating distances from a center of therespective determined pixels to the beam-forming curve; and setting theweights based on the calculated distances.
 20. The method of claim 19,wherein the weights are set to be in proportional to or inverseproportional to the calculated distances.
 21. The method of claim 17,wherein the step of detecting the pixels corresponding to each of thesampling data, further comprises: setting a sampling data set forselecting pixels, which the respective sampling data are used as pixeldata thereof, among the sampling data; and selecting pixelscorresponding to respective sampling data of the sampling data set. 22.The method of claim 17, wherein the step of detecting the pixelscorresponding to each of the sampling data, further comprises:performing a down-sampling process upon the reception signals to formdown-sampled data.